Conventionally, edge detection is carried out for image data obtained from X-ray imaging apparatus, non-destructive testing apparatus and so on. This process is an important step often used for improvement in image quality such as avoidance of artifacts due to vertical luminance differences, or for automatic detection of tissues and lesions.
Most basically, there is a method which finds a difference in pixel value to adjacent pixels, and determines the pixel to be an edge or tissue boundary when the difference is large. There is also a method which highlights a variation by applying a high pass filter (HPF) to image data, and determines the pixel to be an edge or tissue boundary when its value is large (see Patent Document 1, for example).
[Patent Document 1]
Patent Application H7-134418